Minimization of acoustic echo effects in a microphone boot

ABSTRACT

A microphone boot system for reducing acoustic echo effect has a first compression structure; a first member of a microphone boot pressing against the first compression structure; second member of the microphone boot pressing against the first member of the microphone boot at an interface; a microphone interposed within a cavity formed by the first member of the microphone boot and the second member of the microphone boot; and a second compression structure juxtaposed against the second member of the microphone boot, such that the first compression structure and the second compression structure acting in concert form an acoustic seal at the interface. A method of reducing acoustic echo effect involves forming a first member of a microphone boot; forming a second member of a microphone boot; interposing a microphone between the first member of the microphone boot and the second member of the microphone boot; and applying a compressive force to the first member of the microphone boot and the second member of the microphone boot so as to form an acoustic seal between the first member of the microphone boot and the second member of the microphone boot at an interface thereinbetween.

BACKGROUND OF THE INVENTION

The present invention relates to minimizing acoustic echo effects, andmore particularly to minimizing acoustic echo effects in a microphoneboot. Even more particularly, the present invention relates tominimizing acoustic echo effects in a noise canceling microphone bootfor a portable radio, such as a portable cellular telephone.

A major challenge faced by the designer of portable radios, such asportable cellular telephones is posed by what is known as "acoustic echoeffect". This effect occurs when sound emitted from a speaker in aportable radio is transmitted to and received by a microphone in thesame portable radio. For example, when a first person is talking to asecond person, as the first person's voice is emitted from the speakerin the second person's portable radio, it may be picked up by amicrophone in the second person's portable radio, and consequently,transmitted back to the first person. Absent any mechanism forminimizing or preventing "acoustic echo effect", the results of thistransmission back to the first person is that the first person's voiceis emitted from the speaker of the first person's portable radio, thus"echoing" the first person's own voice transmissions.

Acoustic echo effect is problematic in portable radios, such as portablecellular telephones, because of their small size and thus short distancebetween the microphone and speaker, and is particularly problematic indigital portable radios, such as digital cellular telephones (e.g.,TDMA, CDMA, GSN and the like), and even more problematic in satellitetransceivers, because of the greater delays present in digital andsatellite environments. Although it is inevitable that some soundemitted from a speaker in a portable radio will be picked up by amicrophone in the same portable radio, acoustic echo effect can beminimized through an effective seal around the microphone within suchportable radio's housing. This seal serves to minimize the amount ofsound entering the microphone from within the portable radio's housing,which accounts for the majority of acoustic echo effect. As a result,most portable radios employ a "boot" made from rubber-like material thatencloses its microphone and provides a seal against plastic housings ofthe portable radio so as to prevent sound from entering the microphonefrom within the plastic housings.

Boot designs commonly employed tradeoff performance (i.e., effectivityof the seal formed around the microphone) for manufacturablity (i.e.,ease and speed of assembly), or vice versa. The primary reason for thistradeoff is that the microphone typically requires two leads (either inthe form of wires or a thin plastic flex conductor in which a pair ofconductors are encompassed or on which such conductors are fused) inorder to connect the microphone with a circuit board within the plastichousings. As a result, there is generally a compromise in the integrityof the seal at the point or points from which these two leads emergefrom the boot. If the point or points at which the leads emerge issealed well, then assembly becomes highly difficult, because the leadsmust be squeezed through tight openings in the microphone's boot. On theother hand, if the point or points at which the leads emerge is notsealed well, then assembly is simplified, but acoustic echo may beworsened because sound is able to enter the microphone through thesepoints.

The present invention advantageously addresses the above and otherneeds.

SUMMARY OF THE INVENTION

The present invention advantageously addresses the needs above as wellas other needs by providing an approach to minimizing acoustic echoeffects in a microphone boot.

In on embodiment, the invention can be characterized as a microphoneboot system for reducing acoustic echo effect. The microphone bootsystem has a first compression structure, such as a front housing; afirst member of a microphone boot pressing against the first compressionstructure; a second member of the microphone boot pressing against thefirst member of the microphone boot at an interface; a microphoneinterposed within a cavity formed by the first member of the microphoneboot and the second member of the microphone boot, such as in a recesswithin the first member of the microphone boot, and preferablyenveloping the microphone within the first member of the microphone bootand the second member of the microphone boot; and a second compressionstructure, such as a rear housing pressing against the second member ofthe microphone boot, such that the first compression structure and thesecond compression structure acting in concert form an acoustic seal atthe interface. Preferably also, the first member of the microphone bootand the first compression structure, and the second member of themicrophone boot and the second compression structure form respectiveacoustic seals thereinbetween as well.

In a variation of the above embodiment, the microphone boot system hasan electrical conductor coupled to the microphone. The electricalconductor is interposed between the first member of the microphone bootand the second member of the microphone boot at the interface betweenthe first member of the microphone boot and the second member of themicrophone boot. The electrical conductor is preferably a flexconductor, and preferably is fashioned to form a radial flange aroundone end of the microphone that occupies the interface region, with thefirst member of the microphone boot and the second number of themicrophone boot forming respective seals on either side of the flange.

In another embodiment, the present invention can be characterized as amethod of reducing acoustic echo effect. The method involves forming afirst member of a microphone boot; forming a second member of amicrophone boot; interposing a microphone between the first member ofthe microphone boot and the second member of the microphone boot; andapplying a compressive force to the first member of the microphone bootand the second member of the microphone boot so as to form an acousticseal between the first member of the microphone boot and the secondmember of the microphone boot at an interface thereinbetween.Preferably, also, respective acoustic seals are formed between a firsthousing member and the first member of the microphone boot, and betweenthe second housing member and the second member of the microphone bootwhen the first housing and the second housing are assembled and therebyapply the compressive force to the first member of the microphone bootand the second member of the microphone boot.

In a variation, the method also involves interposing a conductor betweenthe first member of the microphone boot and the second member of themicrophone boot at the interface region, and preferably interposing aflex conductor that forms a radial flange at one end of the microphonebetween the first member of the microphone boot and the second member ofthe microphone boot and wherein the seal is formed on respective sidesof the radial flange by the first member of the microphone boot and thesecond member of the microphone boot.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentinvention will be more apparent from the following more particulardescription thereof, presented in conjunction with the followingdrawings wherein:

FIG. 1 is a perspective view of a portable radio and microphone bootassembly, including a microphone and a ringer, in accordance with oneembodiment of the present invention;

FIG. 2 is a perspective view of a lower member of the microphone boot ofFIG. 1;

FIG. 3 is side view of the lower member of the microphone boot of FIG.2;

FIG. 4 is a perspective view of an upper member of the microphone bootof FIG. 1;

FIG. 5 is a side view of the upper member of the microphone boot of FIG.4; and

FIG. 6 is a side view of the upper and lower members of the microphoneboot of FIG's 2 through 5, assembled together with the microphone andringer of FIG. 1.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the presently contemplated best mode ofpracticing the invention is not to be taken in a Limiting sense, but ismade merely for the purpose of describing the general principles of theinvention. The scope of the invention should be determined withreference to the claims.

Referring first to FIG. 1, shown are an upper housing 100, a lowerhousing 102, an upper member 104 of a microphone boot, a lower member106 of a microphone boot, a microphone 108, a flex conductor 110, and aringer 112.

As can be seen, as represented by dashed lines, the upper and lowerhousings 100, 102 snap together and are secured in place by tabs 114,such as is known in the art. In the process of snapping the housings100, 102 together, the upper and lower members of the microphone boot104, 106, which are sized to be slightly larger, i.e., from, forexample, between 0.01 and 0.03 inches of interference, than a spacebetween a sound directing structure 116 in the upper housing 100 and thesound directing structure 118 in the lower housing 102, so as tocompress the upper and lower members 104, 106 of the microphone boottogether upon assembly of the upper and lower housings 100, 102.Preferably, Butyl rubber is used to make the upper and lower members ofthe microphone boot 104, 106, however, numerous materials with acousticinsulating properties can be used within the scope of the presentembodiment. The sound directing structures 104, 106 of the upper andlower housings lead to respective sound ports 120, 122 through whichsound enters the upper and lower housings 100, 102. From the sounddirecting structures 120, 122, the sound entering the upper and lowerhousings 100, 102 is directed respectively, through the upper and lowermembers 104, 106 of the microphone boot to the microphone 108. A radialflange 115 formed from the flex conductor 110 is adjacent to one end ofthe microphone 108 and the microphone 108 is compressed between and heldwithin the upper and lower members 104, 106 of the microphone boot,which form respective seals against respective sides of the radialflange formed by the flex conductor 110 at one end of the microphone 108such that sound is not able to or is highly impeded from entering themicrophone boot other than through the sound ports 120, 122 in the upperand lower housings 100, 102.

The compression applied to the upper and lower members 104, 106 of themicrophone boot is sufficient to form the seals against the respectivesides of the radial flange formed 115 by the flex conductor 110 adjacentto one end of the microphone 108 at the interface of the upper member104 of the microphone boot and the lower member 106 of the microphoneboot. The radial flange 115 occupies the interface region between theupper member of the microphone boot 104 and the lower member of themicrophone boot 106. The flex conductor 110 also electrically couplesthe microphone 108 to circuits (not shown) within the housing 100, 102,such as portable radio circuits. The compression applied to the upperand lower members 104, 106 of the microphone boot is as a result of theupper member of the microphone boot 104 and the lower member of themicrophone boot 106 being slightly larger than the space between theupper sound directing structure 116 and the lower sound directingstructure, such as an interface of from between about 0.01 inches and0.03 inches.

Also shown is a ringer 112, which in the present embodiment alsosupported by the microphone boot between an upper ringer supportingstructure 124 of the upper member 104 of the microphone boot, and alower ringer supporting structure 126 of the lower member 106 of themicrophone boot. In the embodiment shown, the flex conductor 110 fromthe microphone 108 passes between the upper ringer supporting structure124 and the ringer 112, which serves to hold the flex conductor 110securely in place, and prevent stresses on the flex conductor 110 fromjeopardizing the integrity of the seal around the microphone 108, asformed by the upper and lower members 104, 106 of the microphone boot.

The lower ringer supporting structure 126 includes an opening 130, whichupon assembly of the upper and lower members 104, 106 of the microphoneboot and the upper and lower housings 100, 102, is adjacent to a ringerport 132 through which sound emanating from the ringer 112 exits thelower housing 102, so as to notify a user that, for example, an incomingcall is being received.

Wires 136 connecting the ringer 112 to circuits within the upper andlower housing 102, 104 pass through and make electrical contact with theflex conductor 110 and pass into clearance holes 134, 136 in the upperringer supporting structure 124. The wires 136 are connected to, e.g.,soldered to, respective conductors within the flex conductor by piercingthrough the flex conductor 110 at such conductors.

Referring next to FIG. 2, shown is the upper member 104 of themicrophone boot, including the upper ringer supporting structure 124.Also shown is a hole 200 into which the microphone is placed duringassembly, the holes 134 through which the wires of the ringer pass, anda notch 202 through which the flex conductor passes.

Referring next to FIG. 3, shown is the upper member 104 of themicrophone boot, including the upper ringer supporting structure 124,the opening 200 into which the microphone is placed, and an opening 300that directs sound from the upper sound port into the microphone, aschanneled by the upper sound directing structure.

Referring next to FIG. 4, shown is the lower member 106 of themicrophone boot, including the lower ringer supporting structure 126, aswell as an opening 400 into which sound entering the lower sound port ischanneled into the microphone by the lower sound directing structure.

Referring next to FIG. 5, shown are the lower member 106 of themicrophone boot, including the lower ringer supporting structure 126,the opening 130 in the lower ringer supporting structure, and theopening 400 in the lower member of the microphone boot through whichsound from the lower sound port is directed by the sound directingstructure.

Referring next to FIG. 6, shown are the upper and lower members 104, 106of the microphone boot, including the opening 200 into which themicrophone is inserted, the opening 300 in the lower member of themicrophone boot into which sound enters from the lower sound port, andthe opening 400 in the lower member of the microphone boot through whichsound enters from the upper microphone port. Also shown are the flexconductor 110, the microphone 108, the ringer 112, the upper and lowerringer supporting structures 124, 126, the opening 130 in the lowerringer supporting structure through which sound from the ringer 112exits into and through the ringer port, and one of the holes 134 in theupper ringer supporting structure 124 into which one of the wires 136connected to the ringer 112 passes.

In operation, a seal 600 is formed around the microphone at theintersection (or interface) of the upper member 104 of the microphoneboot, and the lower member 106 of microphone boot, which form respectiveseals against respective sides of the radial flange 115 formed by theflex conductor at one end of the microphone 108 so as to prevent orimpede sound emanating from within the upper and lower housings fromentering the microphone 108. Such sound can, for example, come from aspeaker located within the upper and lower housings and is thepredominant source of the acoustic echo effect.

Advantageously, no tedious threading of microphone wires through tinyholes is needed to assemble the microphone boot, because the flexconductor 110 is an integral part of the seal 600 at the interface andpasses out toward the ringer 112, without any breaking of the seals suchas would be necessary to provide passage for wires out of the microphoneboot. This advantageous feature is as a result of the fact that, inaccordance with the present embodiment, the seals are formed by thejuxtaposition of relatively flat surfaces of the upper member of themicrophone boot 106 and one side of the flex conductor 110 and thejuxtaposition of relatively flat surfaces of the lower member of themicrophone boot 104 and another side of the flex conductor 110, thussandwiching the flex conductor 110 between the upper and lower members104, 106 of the microphone boot. Further advantageously, the seal 600 isformed when the upper and loser housings are snapped together as aresult of compressive forces imposed on the microphone boot by the upperand lower sound directing structures and the upper and lower housings.Advantageously, assembly of the upper and lower housings in this way isnot only an already necessary step, but also a quick and simple step ascompared to the tedium of threading wires through holes.

While the invention herein disclosed has been described by means ofspecific embodiments and applications thereof, numerous modificationsand variations could be made thereto by those skilled in the art withoutdeparting from the scope of the invention set forth in the claims.

What is claimed is:
 1. A microphone boot system for reducing acousticecho effect comprising:a first compression structure; a first member ofa microphone boot juxtaposed against the first compressive structure; asecond member of the microphone boot completely, acoustically sealinglypressing against the first member of the microphone boot at an interfacetherebetween; a microphone interposed within a cavity formed by thefirst member of the microphone boot and the second member of themicrophone boot, the interface encircling the microphone;a secondcompression structure juxtaposed against the second member of themicrophone boot, the first compression structure and the secondcompression structure acting in concert to cause said completelyacoustically sealingly pressing and to thereby form an acoustic seal allalong the interface; and an electrical conductor coupled to saidmicrophone, and being acoustically sealingly interposed between saidfirst member of said microphone boot and said second member of saidmicrophone boot at said interface.
 2. The microphone boot system ofclaim 1 wherein said electrical conductor comprises:a flex conductorincluding said electrical conductor.
 3. The microphone system of claim 1further comprising:a radial flange extending from said microphone, theradial flange being interposed between said first member of saidmicrophone boot and said second member of said microphone boot.
 4. Themicrophone boot system of claim 3 further comprising:a flex conductorincluding said electrical conductor and forming said radial flange atone end of the microphone.
 5. The microphone boot system of claim 4further comprising:a first audio passage in said first member of saidmicrophone boot, the first audio passage providing a conduit throughwhich audio waves reach said microphone.
 6. The microphone boot systemof claim 5 further comprising:a second audio passage in said secondmember of said microphone boot, the second audio passage providing anadditional conduit through which audio waves reach said microphone. 7.The microphone boot system of claim 6 further comprising:a first audioport, coupled to said first audio passage, in said first compressionstructure; a second audio port, coupled to said second audio passage, insaid second compression structure.
 8. The microphone boot system ofclaim 7 wherein said first, compression structure comprises a fronthousing member, and said second compression structure comprises a backhousing member.
 9. The microphone boot system of claim 8 wherein saidfirst member of said microphone boot includes a first ringer supportingstructure, and wherein said second member of said microphone bootincludes a second ringer supporting structure.
 10. The microphone bootsystem of claim 9 further comprising:a ringer juxtaposed between saidfirst ringer supporting structure, and said second ringer supportingstructure.
 11. The microphone boot system of claim 1 furthercomprising:a radial flange extending from said microphone, the radialflange being interposed between said first member of said microphoneboot and said second member of said microphone boot.
 12. A method ofreducing acoustic echo effect comprising:forming a first member of amicrophone boot; forming a second member of a microphone boot;interposing a microphone within a cavity formed by the first member ofthe microphone boot and the second member of the microphone boot;applying a compressive force to the first member of the microphone bootand, the second member of the microphone boot so as to form an acousticseal between the first member of the microphone boot and the secondmember of the microphone boot at an interface thereinbetween; andacoustically sealingly interposing an electrical conductor, coupled tothe microphone, between the first member of the microphone boot and thesecond member of the microphone boot at the interface.
 13. A method ofreducing acoustic echo effect comprising:forming a first member of amicrophone boot; forming a second member of a microphone boot;interposing a microphone within a cavity formed by the first member ofthe microphone boot and the second member of the microphone boot;applying a compressive force to the first member of the microphone bootand the second member of the microphone boot so as to form an acousticseal between the first member of the microphone boot and the secondmember of the microphone boot at an interface thereinbetween; andinterposing a conductor between the first member of the microphone bootand the second member of the microphone boot at the interface.
 14. Themethod of claim 13 wherein said applying of said compressive forceincludes coupling a front housing member to a second housing member. 15.The method of claim 14 further comprising:a flange of said microphonebetween said first member of said microphone boot and said second memberof said microphone boot at said interface region.
 16. A microphone bootsystem for reducing acoustic echo effect comprising:a first compressionstructure; a first member of a microphone boot juxtaposed against thefirst compressive structure; a second member of the microphone bootpressing against the first member of the microphone boot at aninterface; a microphone interposed within a cavity formed by the firstmember of the microphone boot and the second member of the microphoneboot; a second compression structure juxtaposed against the secondmember of the microphone boot; an acoustic seal formed all along theinterface and around the microphone; andan electrical conductor coupledto the microphone, member of the microphone boot and the second memberof the microphone boot at the interface.
 17. The microphone boot systemof claim 16 wherein the first member of the microphone boot and thesecond member of the microphone boot is made of acoustically insulatingmaterial.